The present invention relates to article handling apparatus and, specifically, to apparatus for placing elongated objects such as spacing sticks at spaced intervals on the top layer of articles being stacked. In a specific embodiment, the present invention is employed to place spacing sticks between layers of green cut lumber to provide ventilation spaces between the layers of lumber which will greatly improve circulation of drying air between the layers when the stack is placed in a drying kiln.
In many industrial operations, it is desirable and sometimes necessary to place spacing members between layers of products or goods or raw material that is being stacked for subsequent treatment or even for storage. The procedure for placing spacing members is often time consuming and very labor intensive, particularly where large surface areas must be traversed by the spacing members at fixed intervals. In one such environment where cut lumber is delivered from a sawmill cutting operation to a drying kiln, the use of spacing members is highly desirable so that the operation of the kiln can be efficiently conducted. However, while the lumber cutting operation can be highly automated, no satisfactory apparatus has been developed to insert suitable spacing members in precise locations over the top of a layer of cut raw or green lumber in constructing a stack of raw lumber which is to be inserted in a drying kiln to cure the lumber. While it has been found that the use of spacing members in the operation of a wood drying kiln is essential for proper operation of the kiln and proper curing of the green lumber, manual labor has been almost exclusively employed to insert spacing sticks in adjacent layers of the stacked lumber. This has resulted in a severe restriction in the throughput production capacity of a lumber mill.
Attempts to solve the production problem resulting from the need to insert spacing members in a stack being formed have, in general, not produced apparatus that can locate with any precision spacing members in locations desired to enable the construction of a stable stack of material. Precise positioning of the spacing member is important in a wood curing operation since an unstable stack will often induce bowing in the improperly supported wood pieces during drying. In addition, other attempts have suffered from the disadvantage that only very precisely formed spacing members can be employed which, clearly, results in increased costs for the user of such apparatus.
It is an object of the present invention to provide a material handling apparatus which can be employed to locate with precision any desired number of spacing members on top of a layer or in a plane in precisely defined locations very rapidly and without the need for precisely manufactured spacing members.
According to the present invention, in a preferred embodiment, a plurality of individual magazines for receiving spacing members are disposed above a stacking area. At the lower portion of each magazine, which may be gravity operated, arrays of pairs of guide arms are provided which will operate to remove a single spacing member from an associated magazine and deliver the spacing member to a precise location on a subjacent top layer of the articles being stacked thereunder. The guide means are then withdrawn to permit a worker to insert another layer of articles on top of the thus disposed and properly spaced spacing members. The operation may be repeated as desired until a stack of a desired size is completed. The formed stack is then removed for subsequent processing as the nature of the material will require. The guide arms are all of identical construction and each will include a first guide arm which has one end pivotally secured to the periphery of a cam disk which is mounted on a drive shaft. A second guide arm has one of its ends pivotally mounted on a fixed axis vertically above and slightly offset from the first guide arm. A second guide arm has a slightly longer length than the first guide arm and has its lower free end provided with a hook to grab and restrain movement of a spacing member disposed between the guide arms. The guide arms interengage intermediate their ends so that when the lower guide arm is moved upwardly by its cam disk operating means, it will, during its travel, engage the upper guide arm and lift the upper guide arm upwardly away from the layer being stacked.
With this arrangement, spacing members can be placed one above each other in each layer of articles being stacked to thereby provide a very stable stacked arrangement which will facilitate subsequent handling such as movement of the formed stack to a subsequent operation such as a drying kiln. In addition, the apparatus can be highly automated so that only a single worker will be required to operate the stack placing apparatus without sacrificing accuracy and speed in the placement of the spacing members in the stack being formed. In addition, the apparatus of the present invention, as described in more detail below, may employ spacing members that vary widely in their external shapes and yet which can be handled with great precision with the apparatus of the present invention.
The foregoing and other advantages will become apparent as further consideration is given to the following detailed description taken in conjunction with the accompanying drawings in which: